Vomiting, nausea and diarrhea after a dinner out? You probably didn't eat some bad seafood; an employee just forgot to wash his or her hands.

While norovirus has been called the "cruise ship sickness," only 1 percent of outbreaks happen on cruises. It's on your normal night out that you have to be careful, as 70 percent of norovirus outbreaks are caused by infected food workers, according to a recent CDC study.

In the U.S., food employees are legally required to "wash hands before returning to work," as the ubiquitous sign in restaurant bathrooms reads. But, workers still forget: employees only practice proper hand washing 1 of 4 times that they should.

Of outbreaks caused by infected workers, 54 percent involve employees touching ready-to-eat food with their bare hands. That means the contamination doesn't happen during food preparation, but instead in the final stages of getting foods such as washed fruits, salads or baked goods to the customer.

What can employers do to stop contaminating customers? The No. 1 solution is to follow already established food safety laws, especially as they apply to hand washing.

Another way to keep contamination at bay is to eliminate sick employees from the kitchen. One in 5 service workers have showed up to work while sick with vomiting and diarrhea. The reason? They're worried about losing their jobs or leaving coworkers short staffed. Establish policies such as paid sick leave that encourage workers to stay home when ill and create a staffing plan that includes on-call workers to keep these norovirus ticking-time-bombs out of the kitchen.